Process for treating crude oil



Sept. 20, 1932.

PRESSURE TOWER S. P. COLEMAN PROCESS FOR TREATING CRUDE URL Filed April 19.

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2 Sheets-Sheet l Sept 20, 1932 s. P. coLEMAN 1,877,811

PROCESS FOR TREATING CRUDE OIL Filed April 19. 1928 2 Sheets-Sheet 2 5 T'ILL M7112 liv/La7' u Eis @brom/mj vlitented Sept. 20, 1932 UNITED STATES PATENT OFFICE STEWART P. COLEMAN, OF HOUSTON, TEXAS, ASSIQNOR TO STANDARD OIL DEVELOP- MENT COMPANY, A CORPORATION OF DELAWARE `PROCESS FOR TREATING CRUDE OIL Application mea April 19,

. followine; description andl the drawings which illustrate appa the rprocess. y y

In the drawings, Fig. t is a semi-diagrammatic drawingT in elevation ot an apparatus constructed accordingY to my invention and indicates the flow ol oil.

"Fiat lZis a. scmi-diagrammatic drawing" in elevation ot a moflitication oli the apparatus,

atus tor carrying out .showingT also semi-diagrrammaticallv means "lor purification of the oil and subsequent blending.

` In the distillation of crude oil. a large volunie of Vas is evolved with the oil vapors and on condensation ot the vapor in the worms, gas `is withdrawn. saturated with gasoline. lt is customary to recover the gasoline held by the gras either by compression and cooling" or b v absorption or adsorption, as is well known. These recovery processes are expensive and amonef the. advantages ot my invention. the eliminationof recovery is to be noted@ Other advantages will be apparent to those skilled in the. art.

Referring to the drawings. Fig. L a plurality of stills are shown arranged in a battery such as is customary for the distillation of crude oil. `Four .stills` 4, 5. 6. and 7 are shown and each is surmounted by a tower 3., which may be ot any preferred desi an but is preferably ot the bubble cap plate type. For skimmingF crude oil, av single still or perhaps two or three onlv is desirable. but it the' crude is to be run to a low gravity pitch bottoms. a greater number.v say ten or twelve, maybe advantageously employed. Crude oil is forced by a feed pump 1. under pressure through Coils 2 which are located in the upper portions ot the towers 3. Preheated oil is collected in line 8 andis discharged into a pressure tower 9 at an intermediate point between the `top and bottom. 10 is provided in the upper portion of tower A cooling coil 1928.` Serial No. 271,172.

9, which may be a bubble cap tower similar to towers P, except huilt to stand pressure of 10U to 30() pounds per square inch. apor line 11 communicates with a worm 'l2 and condensate flows therefrom to a pressure Storage tank lf. which is provided with a vent pipe 13a and liquid discharge. line 13?).

Tower E) is enlarged at itshase as indicated at 111-. and a line l5 is provided tor withdrawal ot' oil` a partof which is Jforced hy pump 16 through heater 1i' and back to lflb v line 1S. The remainder ot the oil flows through pipe l?) and is discharged into still l through pipe Q0 or into tower 3 ot still 4v by line '21. Bottomsfrom each still is conducted to the tower ot the next succeeding' still by tlow line 23. Pumps maybe provided tor this purpose but it is preterahle to move the oil "by inieetion ot steam into the flow line as at 14. The. final residuum from the last still 7 is conducted to storage (not shown) by line 25. Each tower is fitted with a vapor `line 2li. which conducts the oil `raporized in each still to a separate worm (not shownl. and then to storage. as is the usual practice.

Tn Fig. Q. a single crude still is shown in side4 elevation and the `crude oil. preheated by passage through coils Q. is conducted by line 8 to a heat exchanger Q7 before discharge into tower Q. The tower is mount-ed on a still 14er. which `mav be directly heated and is fitted with partial. condenser 10. as before. The vapor `troni tower 9 ie conducted by vapor line .28 to an intermediate point of a secondary tower Q9. which is preferably of the bell can type and is fitted with a cooling coil 30 in its upper portion. A vapor line 11 conducts vapor from the top of tower 29 and at its lower end. tower 29 is enlarged into a still 3Q in which a coil 33a, is disposed. Bottoms from still 14n, mar be conveniently used to heat still 82. and eoil 33a, is connected by pipe 33 so that the hot oil may flow there through and finally by line 34 to heat eX- ehangerQT. From the heat exchanger the oil flows as before to the crude battery by line 34a and is discharged into Still l by line 20, or into tower 3 by line 21. Bottoms from 36 through cooler 37 and to pressure storage 13 as in Fig. 1.

Vapors from the tower 3 are conducted by vapor line 26 to worm 26a and after condensation the distillate is led by Q6?) to a receiving pan 39. Pump 40 takes oil from the pan and forces it through a mixer 41 which is fitted with bailles 42 to provide a ltortuous path.

Caustic soda, lor any other liquid treating ageut such as sulphuric acid or doctor7 solution, may be used in place of the soda, depending on the particular oil treated, as will be familiar to those skilled in the art. The mixture of oil and treating agent is allowed to separate in settling chamber 14, spent soda being discarded by pipe 45. Pump 46 forces the oil through a second mixer 41 similar to the first and water may be added by pump 43. The mixture is again settledin 44 and water discarded by line 45 while oil is led to blending tank Llhy pipe 46. A part or all of therlight distillate collected in `pressure tank 13 may also be admitted to tank 47 by line 13b and the blend led to storage by line 4S.

It will be readily understood that other treating systems may be used, whether c ontinuous or batch, and if two or more treating agents, such as sulphuric acid and soda are used, mixers similar to 41 may be used for each treating agent. It may be desirablel to redistill the treated oil before blending, as is well known in the art.

` In the operation of my process, crude oil is preheated under pressure and discharged into tower 9 which is maintained at pressure above 25 pounds per square inch but preferably between 50 and 250 pounds per square inch. The exact conditions of pressure and temperature will vary somewhat according to the particular crude and the result desired, as will be discussed below. The oil is preferably heated from 250 to 375 F. before discharge into tower 9 and tempera'- ture in the still'la or the enlarged portion 14 of tower 9 is generally about 50 F. more or less above the feed temperature. Cooling water is preferably circulated through coil 10 although othercooling media might be used and temperature and quantity are suitably adjusted for holding the vapor temperai ture at about 150 F.. although this temperature will depend on the pressure maintained,

as will be understood.

-`In tower 9 fixed gases are substantially completely rectified from the crude and the product flowing from the base of the tower is forwardedto the crude stills. On distillation, ga`soli1ie".ai1d kerosene may be removed and condensed in the usual manner but without losses due to gas saturated with gasoline. No gas, or substantially none, will be evolved, except for a relatively small quantity of cracked gas from the last few stills of the battery.

`where substantial cracking occurs.

The apparatus, as illustrated in F ig. l, is adapted to rectify the crude and to produce a stripped crude of low vapor pressure containing substantially no butane and if desired, pentane can also be included in the distillate which is condensed and collected in the pressure receiver 13. Pressure above 50 pounds per square inch is preferable so that butane in the distillate may be condensed with ordinary cooling water. may be used for any purpose gasoline fractions of the crude oil after such fractions have received whatever purification treatment may be required, such* as tretment with sulphuric acid, alkali, or doctor solutions or any other treatmentknown to the petroleum industry. u'

.In Fig. 2 the apparatus is adapted to rectify the crude and to produce anintermediate fraction at line 36, which comprises the light liquid or liquefiable hydrocarbons, such as butane and pentane, although I prefer'to obtain substantially pure butane. In this modification of my invention, vapors leaving thev system by line llare substantially free of butane and heavier hydrocarbons, and may be led directly to burners, for use as fuel or otherwise. In this ease, where separation between butane and propane is intended, I prefer to operate at pressure higher than that required in the modification illustrated by Fig. 1, for example between 125-250 pounds per square inch. Temperature ofthe still 14a will be higher than in the ease illustrated by Fig. 1 but should not ,go into the range Butane produced is preferably added to the gasoline fractions after the latter have been treated and may be added in whatever proportion may be desirable.

The crude still battery is operated in the usual manner well known in the art. The temperature of the stills varies from about 350 or 400C. F. inthe first to from 6900 to 695 in the last, in which heavy distilled to pitch bottoms. The crude stills are maintained at substantially atmospheric pressure. and under certain circumstances, it is desirable to -cool the hot oil from the pressure tower 9, asin coil 33a and heat exchanger 27, before discharge into tower 3 atatrnospheric pressure. After passage through the pressure towers, it is found that the vapor pressure of the crude is much reduced, for example to 50 to 75 mm. at 75 F. and distillates, being little loss by evaporation in subsequent treating operations.

My invention liudsI particular application to light crude iu which a large amount of gas is present although it is applicable and useful in distilling any crude oil or cut therefrom which contains gas and gasoline, such as pressure distillate or cracking coil distillate.

This distillate desired but it preferred to blend a part or all of it with oil is being free from dissolved gas, showr My invention is not to be limited by anythe temperatures and pressure are so regutheory of the mechanism of the process nor lated that the liquid obtained from the secby any example given merely by way of illus* ond series of zones 1s substantially pure tration but only by the attached claims in butane.' which I Wish to claim all novelty inherent in STEWART P. COLEMAN. 70 the invention.

I claim: l. Improved process or obtaining valuable s products from crude oil which comprises cOnm tinuously preheating the crude under super- 75 Y atmospheric pressure, rectifying the crude under said pressure and at tem erature at which no substantial cracking ta Ves place t produce a liquid distillate comprising butane y and a residue substantially free of butane, 80

and coptinuously dist-illing the residue under substantially atmospheric pressure.

2. Process according to claim 1 in which the crude is rectified under a pressure of from"' 29 25 to 250 pounds per square inch. 4 35 3. Process according to claim 1 in which the crude is rectified under a pressure of from 50 to 250 pounds per square inch.

4. Process according to claim 1 in which g5 the crude is rectified under pressure of from 90 to 250 pounds per square inch and at a temperature of from 250 to 375 F.

5. Process according -to claim 1 in which the cru de is rectified under a pressure of from 3o 50 to 250 pounds per square inch and at a 95 temperature of from 250 to 375 F. 1 6. Process according to claim 1 in which the crude is rectified under a pressure of 125 c0250 pounds per square inch. 85 7.` 'Process I'according' to claim 1 in which 10G i distillate resulting from the distillation under atmospheric pressure is blended with a portion of the liquid'distillate comprising butano.

8. An improvedprocess for obtaining valu- 40 able products from crude oil, comprising pre- 105;

heating the crude under pressure between 125 and 250 pounds per square inch, dischargingA said crude into an intermediate zone of a first series of rectification zones and rectifyui ing the crude therein under full pressure and no at a temperature at which no substantial cracking' takes place to produce vapors com prising butane and a liquid residue, passing the vapors to an intermediate zone of a second series of rectification zones under the same pressure and rectif'yinn,r the vapors therein at temperatures to produce a residual liquid comprisingr butano, withdrawing the v residual liquid from the second series and removing vapors and gases from the second series of rectification zones, withdrawing the liquid residue from the first series of rectification zones, and distilling said residue under atmospheric pressure.

50 9. Process according to claim 8 in which the temperatures and pressure are so regulated that tlie vapor removed from the first series of rectificationzones is substantially free from pentane and higher hydrocarbons.

10. Process according to claim 8 in which 

